Customers at two Birmingham garages are being forced to freewheel their cars off the forecourt - because of interference from nearby phone masts.

Visitors trying to leave National Tyres and Car Spares on the Stratford Road are being forced to push their cars nearly 100 yards out of range of the masts on the roof of the Centre Court office block.

It is believed the mast's rays are interfering with car's immobilizers and alarms.

Clive Carter, from National Tyres garage, and Keith Murphy, from Car Spares, which are both near the mast on Stratford Road, said many customers could not start their vehicles in their forecourts.

Mr Carter said: "This has happened at least 20 times in the last year. The strange thing is that when a car is pushed down the road it starts easily. The mobile phone masts seem to be the only explanation for it."

Dr Gerald Hyland, a phone mast expert and former senior physics lecturer at Warwick University, said the rays were likely to be interfering with the cars' ignition systems.

And he said radiation from the masts could also be damaging our health.

He said: "If these rays are strong enough to cause interference with car alarms, then we should be concerned about what they are doing to our bodies.

" We are much more sensitive to radiation than cars are.

"People want to use mobile phones and you can't use them without a mast, but masts are often placed in insensitive areas and can be stronger than they need to be. They should never be near a workplace or near people."

It is thought that rays from phone masts can also interfere with a car's locking system and unexpectedly activate a vehicle's alarm.

More than 40,000 mobile phone masts have been installed in the UK, and a further 10,000 are needed for the increasingly popular third-generation videophones.